Stoker fuel supply signal switch



June 10, 1952 M. E. KEELE ETAL sToxER FUEL SUPPLY SIGNAL SWITCH 2 SHEETS-SHEET l Filed April 2, 1949 am t? z Smoentor M m fz. M

Gttomeg v June 10, 1952 M. E. KEELE ET AL 2,599,840

STOKER FUEL-SUPPLY SIGNAL SWITCH Filed Apljil 2. 1949v v I '2 sHEETs-sI-IEET 2 Bnventog' Gttorneg Patented June 10, 1952 OFFICE STOKER FUEL SUPPLY SIGNAL SWITCH A Marvin E. Keele and Merle L. Noble,

Blencoe, Iowa Application April 2, 1949, Serial No. 85,196

1 Claim.

Our invention relates broadly to heating apparatus and to a'control system therefor, and more specifically to an apparatus for automatically signaling the fuel supply in the hopper of a stoker.

It is well known that throughout the country some thousands of janitors are employed taking care of buildings in which their main activity is the responsibilityfconnected with and the care of stokerv furnaces. It is also well known that these furnaces are provided with hoppers needing intermittent filling with Stoker coal, and that between the filling of these of hoppers a janitors constant attention is not needed at the stoker apparatus.

However, in practice, there hasl been the difficulty that a janitor cannot be certain just when the hopper of a Stoker furnace will become empty, since a hopper full of coal is exhausted within different periods of time during different seasons and different parts of the day and in accordance with the normal thermostatic control governing the rate of fuel consumption.

It is therefore an object of this invention to provide a signaling apparatus for signaling a janitor when it is time to refill the hopper of a stoker system.

Another object of the invention is to provide anA apparatus as described having both visible and audible signal means.

Still another object of the invention is to provide a device as described which is adapted to be responsive to the pressure of coal resting thereagainst when the device is secured to the side wall of the hopper of a stoker.

A further object of the invention is to provide a hopper-mounted pressure responsive device as described which is Isealed from contamination by coal dust.

Yet another object of the invention is to provide an object as described employing mercury switches to give a dependable and long lasting signaling device.

Another object of the invention is to provide a device for reducing the chances of the back-v blowing of flame and coal soot upwardly through an empty hopper, since back-blow frequently soils the walls of homes, and burns out conveyor screws and fire pot rings.

Another object ofthe invention is to provide a device for the purpose described which is sturdy and durable in construction, reliable and efcient in operation, and relatively simple and inexpensive to manufacture, assemble andvutilize.

Other and still further objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment thereof.

In the drawings:

Figure l is a side elevation of a stoker of conventional construction, portions of the fire pot, conveyor tube, and hopper being broken away for showing the interiors thereof, the modification shown in Figure 1 being one in which the same motor is mounted for actuating both the conveyor screw and the blower fan of the system; the signaling device of this invention being attached thereto.

Figure 2 is a view-in-section taken along the line 2-2 of Figure 1.

Figure 3 is a vertical sectional view taken downwardly through the pressure responsive portion of the automatic signal device.

Figure 4 is a view-in-section taken along the line 4 4 of Figure 3; and

Figure 5 is a wiring diagram of a modilication of the blower system showing two separate blower and conveyor motors with the mercury switches and audible and visible signals of this invention secured thereto.

The signal of this invention is adapted to be attached to a Stoker system such as is shown in Figure 1, including a furnace hopper generally indicated at l0, having a fire pot opening l2, and a conveyor tube i4 disposed in communication with the opening l2 and extending outwardly and transversely of the furnace proper I0.

The tube I!! is disposed in communication with the bottom end of a hopper, generally indicated at I6.

The hopper le is of the shape of a frustrum of a cone, being provided with inclined walls tapering downwardly toward the lower end thereof, which latter is in communication with the upper side of the conveyor tube ifi.

A conveyor screw I6 is disposed in the tube Hi and is provided with a shaft 2S, Iwhich latter eX- tends outwardly from the speed-reducer 22, which latter is drivably secured to an electric motor 21%.

The motor 24 can be used, if desired, for driving the conveyor only, and a separate motor 26, as shown only in Figure 5, can be used for driving a blower fan 2S. However, the motor 24 can also be used to drive both the conveyor screw t8 and the blower 2&3 by providing a belt 34 on the motor 24 and drivably secured to the blower fan 23.

The blower fan 28 is provided with a blowing tube 40 disposed in communication with the furnace l0 in any suitable manner.

As best seen in Figure 2, this invention includes a pressure responsive device positioned in a boxlike housing generally indicated at 58. The pressure responsive device 58 is provided with a circular mounting or spacing frame 52 which is disposed in use extending through and to the inside of the hopper` I6 and adjacent a lower end thereof.

The mounting 52 has o, flexible dust-protecting cover `54 disposed thereacross, the mounting 52 having a circular opening therein for receiving the circular cover 54. The cover 54 is preferably formed of an oil-resistant rubber of the synthetic type such as neoprene.

An annular rim 58 is provided having bolts 88 disposed therethrough for securing the cover 54 against the mounting 52.

The device 58 further includes a pressure plate 18, `which latter is disposed in parallelism with the cover 54 and is closely spaced apart therefrom. The plate 18 has a mounting rod 14 secured thereto and extending at a right angle therefrom in a direction away from the cover 54. The rod 14 is slidably disposed in a suitable mounting sleeve 18, which latter is secured to a frame piece on side wall 88', which latter in turn is adapted to be secured to the hopper adjacent an opening therethrough made for receiving the pressure sensitive device.

The inner end of the rod 14 is shown in dotted lines at 18 in Figure 4, and is adapted to engage a downwardly extending arm '88, which latter is secured swingably upon an axle 82 through a hub 83. The axle 82 is also adapted to rotatably support a mounting member or panel 84 upon which latter two mercury switches 88 and 88 are mounted in suitable spring clips 88, the latter being secured to the member 84 by a platform 85. The latter is pivotally secured to the `rrlember 84 and is adjustably maintained thereto by a bolt 81 and a spring 89 for holding the platform '85 in position on the member 84.

The mounting member 84 is rigidly secured to the arm 88 and is adapted to swing therewith at times `when the rod 14 pushes upon the arzn 88.

The mounting member '84 is further provided with a spring '86 which is of the tension type and is secured at one end to an aperture |88 in the lower end of the mounting member 84. rlChe spring '88 is secured at its other end to an anchor |82 secured to an outer box cover portion or housing |84 of the device 58.r The spring 98 is disposed such that it will tend to urge the member 84 in a direction toward the pressure plate 18.

The mercury switches 88 and 88 are each provided with two terminal wires ||8 and H2, respectively, which are respectively secured each to a different one of two pairs of terminal posts |28 and |22. The latter extend through and are insulated from the cover |84 of the device 58 and are disposed spaced apart from the upper side of the cover |84 by an insulating member |38.

The cover |84 is provided with a plurality of tab portions |48 extending outwardly therefrom for receiving suitable bolts for securing the cover |04 to the arm 88. The wire |44 is secured to a lead-in wire |58 of an electric light signal bulb |52, and is also secured to a terminal |54 of an electrically operated bell |58. The other wire |45 is secured to the opposite terminal |58 of the light |52, and is further secured to a ter-mina] |68 of the bell |58.

Two lead-in wires |18 and |12 are provided coming from a source of electrical supply, not shown, through a plug |13, the latter being shown only in Figure 1.

As best seen in Figure 5, the wiring diagram for the circuit includes the provision of having the wire |18 secured to the terminals |16 and |18, respectively, of the blower and conveyor motors, when two motors are used.

The other terminals of the motors 25 and 24 are each secured to a wire which leads through a post |22 and wire l2 to a contact |82 in the lower one 88 of the mercury switches. The other power lead-in wire |12 is disposed in communication with the opposite contact |84 of the mercury switch 88 through the other post |22 and wire H2. The mercury switch 88 has a ball of mercury |88 therein for connecting the contacts |82 and |84 only at times lwhen the switch 88 is tilted by movement of the pressure plate 10 so that the ball |88 rolls into engagement with the contacts |182 and |84.

The other switch 88 has a ball |98 and two contacts 288 and 282 which are connected, respectively, with the wire |44 through a wire ||8 and post |28, and a wire 284 which leads to the wire |12 from the corresponding wire ||8 and post |28.

In operation, it will be seen that when the hopper is full, coal pressing against the plate 18 through the exible cover 54 will cause the shaft 14 to engage the member 88 for urging the lower end of the mounting 84 to the right, as shown in Figure 3.

The ball |88 is then caused to roll into contact with the contact members |82 and |84 for causing the blower and conveyor to operate.

When the coal supply in the hopper |6 is depleted suficiently, the pressure on the plate 18 will be released and the mounting 84 will be permitted to pivot to the left at its bottom end, as seen in Figure 3, and under the urge of the spring 96.

The ball |88 will then interconnect the contact members 288 and 282 for causing the lighting of the bulb |52 and the ringing of the alarm bell |55. The janitor can then return from his other activities for refilling the hopper I5.

Without the alarm system the janitor would necessarily have to remain within close proximity of the hopper to make frequent and usually unnecessary trips to determine the need of relling. With the present invention, the janitor need make but one trip for each hopper full of coal used and is free between times for other desired activities.

From the foregoing description it is thought to be obvious that a Stoker fuel supply signal constructed in accordance with our invention is particularly well adapted for use by reason of the convenience and facility with which it may be assembled and operated, and it will also be obvious that our invention is susceptible of some change and modication without departing from the principles and spirit thereof, and for this reason we do not wish to be understood as limiting ourselves to the precise arrangement and formation of the several parts herein shown in carrying out our invention in practice except as claimed.

We claim:

A coal bin fuel level indicating device comprising a hopper having a side wall with an opening therethrough, a sleeve mounted on said side wall, positioned around the opening and extended from the side wall, a box-like housing extended from the side of the side wall from which the sleeve extends and positioned around said sleeve, a circular spacing frame having a continuous beveled flange around the periphery and having an annular recess therein mounted on the face of the side wall opposite to that from which the sleeve extends and also positioned around the opening in the said wall, a resilient circular cover in said spacing frame and positioned with the edge thereof in the said recess, means securing the edge of the cover in the recess, an axle mounted in said box-like housing and positioned with the axis thereof above and in a plane perpendicular to the axis of said sleeve, a panel having a hub extended therefrom suspended from and swingably mounted through the hub thereof on said axle, an arm depending from the hub and secured at one edge thereof to said panel, said arm positioned transversely of an axis extended through said sleeve, a rod slidably mounted in the sleeve with one end extended to engage said arm and with the other extended into said spacing frame, a pressure plate carried by the end of the arm extended into the spacing frame, said pressure plate spaced from and positioned parallel to the said resilient circular cover whereby weight against the cover slides the rod through the sleeve and the rod actuates the panel, mercury tubes with spaced contacts in the ends thereof carried by the panel, said contacts of one tube being positioned in the end thereof opposite to the end in which the contacts of the other tube are positioned, and a spring attached to the panel and housing for urging the arm of the panel against the end of said rod.

MARVIN E. KEELE.

MERLE L. NOBLE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,891,319 Stayton Dec. 20, 1932 1,892,084 Sprague Dec. 27, 1932 1,892,790 Smelser Jan. 3, 1933 1,911,530 Raisch May 30, 1933 2,441,480 Francis May 11, 1948 2,442,275 Mayer May 25, 1948 

